The invention relates to a Ground Fault Circuit Interrupter (GFCI), which in general, is technically well known. A GFCI is designed to protect the user from electrocution when a hazardous ground fault occurs. Household electrical appliances, home bathrooms and kitchens are typically required to be equipped with electrical circuits having a ground fault protection function.
GFCIs are described in several U.S. Patents. In these devices the power supply is immediately cut off when some of the operating components are damaged. This prevents the power supply from connecting to the line terminal via a load terminal if the GFCI is reversely miswired.
Such devices, however, have several disadvantages. First, when the device trips and cuts the power supply in instances where some of the operating components are damaged, power continues to be supplied to all the components on the circuit board. In addition, the device can still be reset by depressing the reset button, thus enabling unprotected power to reach the device. Particularly, these devices have no ability to trip when the solenoid coil burns. All of these flaws result in unprotected power being permanently supplied to the circuit board even when the GFCI is not operating or is in a tripped state.
Second, as described in many U.S. patents, if the line-load is miswired during installation, the device prevents the power supply from flowing to the line terminal via the load terminal and is non-resettable, but the power supply still exists at the openings of the receptacle face.
Third, if a GFCI reaches its end of life, and should be replaced, the prior art only employs a ground fault simulated fault test circuit which lacks end-of-life simulated fault monitoring to provide an alarm indication.
In the abovementioned cases, the safety of the GFCI circuit device is not ensured, and the users are misled to use unprotected power.